I do this in my custom theme. Override the vote_count function:
function vote_count($post)
{
$this->output('<div class="qa-vote-count '.(($post['vote_view']=='updown') ? 'qa-vote-count-updown' : 'qa-vote-count-net').'">');
if ($post['vote_view']=='updown') {
$this->output_split($post['upvotes_view'], 'qa-upvote-count');
$this->output_split($post['downvotes_view'], 'qa-downvote-count');
}
else {
$post['netvotes_view']['data'] = str_replace( '+', '', $post['netvotes_view']['data'] );
$this->output_split($post['netvotes_view'], 'qa-netvote-count');
}
$this->output('</div>');
}
Note: only the bit in the else clause is actually changed from the original. Now that I think about it, it may be better to just have this:
$post['netvotes_view']['data'] = str_replace( '+', '', $post['netvotes_view']['data'] );
parent::vote_count($post);